Gunmen with suspected links to Hamas security forces in the Gaza Strip killed at least 32 Palestinians and injured dozens in attacks on political opponents and alleged informers during and after Israel's recent war, an international human rights group said Monday.

According to the AP, the New York-based Human Rights Watch called on Hamas to halt what it described as a pattern of arbitrary arrests, torture and summary executions. Human Rights Watch portrayed the attacks as the worst outbreak of internal violence since Hamas seized control of Gaza in June 2007.

Such practices are aimed, in part, at quashing dissent in Gaza and make a mockery of Hamas' claim it upholds the law, the group said. During the war, "Hamas authorities ... took extraordinary steps to control, intimidate, punish and at times eliminate their internal political rivals as well as persons suspected of collaborating with Israel," the report said.

Eighteen Palestinians were killed by Hamas during the three-week war, which ended Jan. 18, and 14 others were killed afterward, the report said. In addition, 49 Gazans were shot in the legs by masked gunmen between Dec. 28 and Jan. 31, and 73 had their arms or legs broken, the report said.

On his part, Hamas spokesman Fawzi Barhoum dismissed the Human Rights Watch report as unbalanced. He said Hamas was willing to investigate any complaints, and denied the group is going after political opponents. According to him, suspected collaborators with Israel who fled Gaza's central prison after it was destroyed in Israeli bombing raids in December were killed by relatives of people they had harmed, not by security forces.

Human Rights Watch said repressive measures are also on the rise in the West Bank. Fatah security forces have been cracking down on Hamas in the West Bank since they seized Gaza. Hamas detainees in West Bank prisons have complained of mistreatment, including beatings and being tied up in painful positions. In January and February, one detainee died in custody, and 31 complained of mistreatment, Human Rights Watch said.